Diagnosis System - Toyota 4-Runner 1985 Repair Manual

FI-22
CHECI{
ENGINE
EFI SYSTEM - Diagnosis System
FI0578
DIAGNOSIS SYSTEM
DESCRIPTION
By analyzing various signals as shown in the later table
(page F 1-25) the ECU detects system malfunctions which
are related to the various operating parameter sensors
or to the actuator. The ECU stores the failure code as-
sociated with the detected failure until the diagnostic
system is cleared by removing the E F I fuse with ignition
switch off.
A "CHECK ENGINE" warning light on the instrument panel
informs the driver that a malfunction has been detected.
The light goes out automatically when the malfunction has
been cleared.
UCHECK ENGINE" LIGHT CHECK
1.
The "CHECK ENGINE" warning light will come on when
the ignition switch is placed at ON and the engine is
1',,'1-
running.
2. When the engine is started, the "CHECK ENGINE" warn-
ing light should go out.
If the light remains on, the diagnosis system has detected
a malfunction in or abnormality in the system.
OUTPUT OF DIAGNOSTIC CODES
To obtain an output of diagnostic codes, proceed as follows:
1. Initial conditions
(a) Battery voltage above 11 volts.
(b) Throttle valve fully closed (throttle position sensor IDL
points closed).
(c) Transmission in neutral postion.
(d) Accessory switches OFF.
(e) Engine at normal operating temperature.
2. Turn the ignition switch to ON. Do not start the engine.
3. Using a sub-wire short terminals T
-El
of the Check Engine
Connector located near the ignition coil.
A03885